Study of Radiolabeled Monoclonal Antibody Anti-B1 for the Treatment of B-Cell Lymphomas and Extended Study to Determine the Safety and Efficacy of Coulter Clone® 131Iodine-B1 Radioimmunotherapy of Advanced Non-Hodgkin's Lymphoma

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Phase I/II, single-center, dose-escalation study of the safety, pharmacokinetics, dosimetry, and efficacy of TST/I-131 TST for the treatment of patients with chemotherapy-refractory or resistant low-grade, intermediate-grade, or high-grade B-cell lymphoma. Subjects received 1 to 3 dosimetric doses followed by a therapeutic dose of TST/I-131 TST. Study BEX104526 was a follow-up study of the long-term safety and efficacy data from the surviving patients who completed at least 2 years of follow-up following administration of TST/I 131 TST on Study BEX104728.

Dosimetric dose: Subjects received 1 to 3 dosimetric doses of TST/I-131 TST, followed by a therapeutic dose of TST/I-131 TST. Subjects received various doses of unlabeled TST (0, 95 or 475 mg) to determine the dose of unlabeled TST that optimized the radiation dose delivered to the tumor by TST/I-131 TST. The unlabeled TST was followed by 5 milliCurie (mCi) of I-131 TST. Serial whole body sodium iodide scintillation probe counts were obtained daily, for at least 5 days, in order to determine the rate of whole body clearance of radioactivity (residence time). The residence time was used to determine the radioactive clearance for the subject and the activity (in mCi) of I-131 required to deliver the desired TBD of radiation during the therapeutic dose. Because 475 mg was determined to be the optimal pre-dose of TST in the first subjects entered, the last 34 subjects received a single dosimetric dose that was preceded by an infusion of 475 mg of TST.

Therapeutic dose: Groups of 3-6 subjects were enrolled at successively higher whole-body radiation dose levels beginning at a total body dose (TBD) of 25 centiGray (cGy). The TBD of each subsequent dose level was escalated by 10 cGy. Subjects who had undergone bone marrow transplantation (BMT) underwent a separate dose escalation (10 cGy TBD increase per dose level) beginning at a TBD level of 65 cGy. The MTD was defined as the highest dose level at which 0/3 or 1/6 subjects experienced dose-limiting toxicity (DLT). DLT was defined as follows:

Any Grade 4 hematologic toxicity (National Cancer Institute [NCI] criteria) lasting greater than 7 days, or Any Grade 3 hematologic toxicity lasting greater than 2 weeks, or Any Grade 3 or 4 nonhematologic toxicity Redosing. Subjects who achieved tumor regression were considered for re-dosing, using the original therapeutic dose of TST/I-131 TST, at the time the tumor was no longer shrinking in an attempt to upgrade their response.

Retreatment. Subjects who achieved partial (PR) or complete response (CR) were considered for retreatment following relapse of their NHL, if progression occurred ≥6 weeks following the therapeutic dose. The original therapeutic dose of TST/I-131 TST was given unless a grade 2 or greater toxicity had been encountered, in which case a reduced dose was administered for the repeat therapeutic dose.

Each subject will undergo two phases of study. The first phase, termed "tracer Study", involves the injection of low-radioactivity doses (about 5 mCi) of 131-I anti-B1 for the purposes of determining the rate of whole body clearance of radiation so that a whole body radiation can be calculated. The calculated whole-body radiation dose per mCi administered can then be used to determined how many mCi will be required to deliver a specified whole-body radiation dose in the second phase of the study for each patient, termed radio-immunotherapy dose in a tracer-projected whole-body radiation dose will be used for dose escalation with a minimum of three subjects per dose level.

131-I anti-B1 is the product of 131-I labeling of the anti-CD20 murine monoclonal antibody and the anti-B1 antibody itself is an intact IgG2a murine monoclonal antibody which has specificity far the CD20 antigen on human B cells. Anti-B1 is a clear, colorless liquid. 131-I labeling of the anti-B1 antibody will be carried out by iodogen technique. Trace labeling of the antibody will involve the labeling of approximately 1 to 3 mg of antibody with 5 mCi of 131-I.

Number of Participants (Par.) During Initial Treatment Exposed to the Indicated Dose Levels of the Therapeutic Dose (TD), Re-dose, and Total Dose (TD + Re-dose) [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Par. (groups of 3-6) received the TD at a total body dose (TBD) of 25 centiGray (cGy) or 65 cGy (par. who had bone marrow transplantation), increasing by 10 cGy increments at each dose level, until the maximum tolerated dose (MTD) was achieved. The MTD was defined as the highest dose level at which 0/3 or 1/6 par. experienced dose-limiting toxicity (DLT): any Grade 4 hematologic toxicity (National Cancer Institute criteria) lasting >7 days, any Grade 3 hematologic toxicity lasting >2 weeks, or any Grade 3/4 nonhematologic toxicity. Not Applicable (NA) indicates that no par. were re-dosed.

Number of Participants During Retreatment Exposed to the Indicated Dose Levels of the TD, Re-dose, and Total Dose (TD + Re-dose) [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Retreatment was administered to participants either at the initial TD of TST/I 131 TST or at a reduced dose if a >=Grade 2 toxicity had occurred after initial treatment, until the MTD was achieved. The MTD was defined as the highest dose level at which 0/3 or 1/6 participants experienced DLT: any Grade 4 hematologic toxicity (National Cancer Institute criteria) lasting >7 days, any Grade 3 hematologic toxicity lasting >2 weeks, or any Grade 3/4 nonhematologic toxicity. Not Applicable (NA) indicates that no participants were re-dosed.

Maximum Tolerated Dose (MTD) of TST/I 131 TST Evaluated in the Study [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Tumor/Organ Dosimetry of TST/I 131 TST for All Predoses (Initial Treatment) [ Time Frame: Serial anterior and posterior gamma whole body scans were obtained 1 hour after the administration of the dosimetric dose (on Day 0), and then daily for at least 5 days until Day 7 ]

Serial whole body sodium iodide scintillation probe counts were obtained from participants approximately 1 hour after the administration of the dosimetric dose and then daily for at least 5 days. Gamma camera images of participants were used to calculate the amount of radiation that accumulated in the target tumor and normal organs (tumor/organ dosimetry). Spleen volume may vary based on disease status, and volume correction allows for a comparison of spleen dose across participants.

Secondary Outcome Measures
:

Tumor/Organ Dosimetry at the Indicated Predoses of 475 mg, 95 mg, and 0 mg (Initial Treatment) [ Time Frame: Serial anterior and posterior gamma whole body scans were obtained 1 hour after the administration of the dosimetric dose (on Day 0), and then daily for at least 5 days until Day 7 ]

The effect of unlabeled TST pre-treatment on targeting of radioactive TST was evaluated. Serial whole body sodium iodide scintillation probe counts were obtained from participants approximately 1 hour after the administration of the dosimetric dose (DD) and then daily for at least 5 days. Initially, participants received either two or three DDs, each of which was preceded by a pre-dose of unlabeled tositumomab (0, 95, or 475 mg) to determine the dose of unlabeled tositumomab that optimized the radiation dose to tumor. The tumor radiation absorbed dose was determined using gamma camera images.

Number of Participants (Par.) With the Indicated Response as Assessed by the Investigator [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Par. with response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).

Number of Participants (Par.) With Confirmed Response as Assessed by the Investigator [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Responses had to be confirmed by 2 separate evaluations occurring >=4 weeks apart. Par. with confirmed response include those with Complete Response (CR: complete resolution of all disease-related radiological abnormalities and the disappearance of all signs and symptoms related to the disease), Clinical Complete Response (CCR: complete resolution of all disease-related symptoms; residual foci, thought to be residual scar tissue, are present), or Partial Response (PR: >=50% reduction in the sum of the products of the longest perpendicular diameters of all measurable lesions; no new lesions).

Duration of Response for All Unconfirmed Responders (CR, CCR, or PR) as Assessed by the Investigator [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Duration of response is defined as the time from the first documented response until disease progression.

Time to Progression of Disease or Death [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Time to progression or progression-free survival is defined as the time from the dosimetric dose to the first documented occurrence of disease progression or death.

Overall Survival [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Overall survival is defined as the time from the treatment start date to the date of death from any cause.

Half-life: Initial Half-life (t1/2 Alpha) and Terminal Half-life (t1/2 Beta) of I 131 TST for the Antibody Predose Levels of 0 mg, 95 mg, and 475 mg [ Time Frame: Blood samples were collected at the end of the infusion (Study Day 0) and at 0.5, 1, 2, 4, 12, 24, 36, 48, 72, 96, and 120 hours following the end of the infusion. ]

t1/2 alpha is the estimated initial or alpha phase half-life in a two-compartmental pharmacokinetic model . t1/2 beta is the estimated terminal or beta phase half-life in a two-compartmental pharmacokinetic model; also denoted as t1/2. Half-life measures how long it takes for the concentration of drug in the blood to decrease by half.

Clearance (CL) of I 131 TST for the Indicated Antibody Predose Levels [ Time Frame: Blood samples were collected at the end of the infusion (Study Day 0) and at 0.5, 1, 2, 4, 12, 24, 36, 48, 72, 96, and 120 hours following the end of the infusion. ]

Clearance is defined as the volume of blood from which drug is removed per unit time and is a measure of the rate at which drug is removed from the body after the dose.

Area Under the Concentration Time Curve (AUC) of I 131 TST for the Indicated Antibody Predose Levels [ Time Frame: Blood samples were collected at the end of the infusion (Study Day 0) and at 0.5, 1, 2, 4, 12, 24, 36, 48, 72, 96, and 120 hours following the end of the infusion. ]

Area under the concentration-time curve from the end of the infusion extrapolated to infinite time. AUC measures how much drug is in the system over time after infusion. ID, injected dose.

Maximum Blood Concentration (Cmax) of I 131 TST for the Indicated Antibody Predose Levels [ Time Frame: Blood samples were collected at the end of the infusion (Study Day 0) and at 0.5, 1, 2, 4, 12, 24, 36, 48, 72, 96, and 120 hours following the end of the infusion ]

Cmax is defined as the maximum observed concentration of the drug in blood.

Volume of Distribution at Steady State (Vss) of I 131 TST for the Indicated Antibody Predose Levels [ Time Frame: Blood samples were collected at the end of the infusion (Study Day 0) and at 0.5, 1, 2, 4, 12, 24, 36, 48, 72, 96, and 120 hours following the end of the infusion ]

Vss is defined as the volume of distribution of the drug at steady state.

Number of Participants Who Developed Human Anti-mouse Antibodies (HAMA Postivitiy) After Receiving Tositumomab [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Tositumomab is a murine (mouse) antibody (immunoglobulin) of the IgG2a subclass. Participants in this study were evaluated to determine whether they developed an immune response to study treatment, as evident by human anti-mouse antibodies (HAMA) after administration of tositumomab and iodine I 131 tositumomab. A positive HAMA value indicates that the participant developed human anti-mouse antibodies above the HAMA assay threshold, and a negative HAMA value indicates either the absence or a below threshold level of human anti-mouse antibodies.

Time to HAMA Positivity From the First Dosimetric Dose (Time From Baseline [Dosimetric Dose] to the First Reported Presence of HAMA) [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Tositumomab is a murine (mouse) antibody (immunoglobulin) of the IgG2a subclass. Participants in this study were evaluated to determine whether they developed an immune response to study treatment, as evident by human anti-mouse antibodies (HAMA) after administration of tositumomab and iodine I 131 tositumomab. A positive HAMA value indicates that the participant developed human anti-mouse antibodies above the HAMA assay threshold, and a negative HAMA value indicates either the absence or a below threshold level of human anti-mouse antibodies.

Number of Participants With the Indicated Type of Infection [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

An infection is the colonization of a host organism by a parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease. Specimen samples of the body fluid are cultured for testing whether the infectious organism is present and grown in the culture media to assess the growth pattern of the organisms present in the specimen. The culture results could be positive or negative. The positive culture results indicate that the tested participant has the infection under investigation, in which case therapeutic treatment with anti-infective is required.

Time to Nadir for the Indicated Hematologic Laboratory Parameters [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Nadir is defined as the lowest laboratory value recorded following the administration of the study medication.

Time to Recovery to Baseline for the Indicated Hematologic Laboratory Parameters [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Time to recovery to baseline is the time required for recovery from nadir values to baseline values.

Nadir Values for the Hematologic Parameters ANC, Platelets, and WBC Count [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Nadir is defined as the lowest laboratory value recorded following the administration of study medication. ANC is a measure of the number of neutrophil granulocytes present in the blood. Neutrophils are a type of WBC that fights against infection. Platelets and WBCs are types of blood cells.

Nadir Values for Hemoglobin, a Hematologic Parameter [ Time Frame: Participants who completed at least 2 years of follow-up in Study BEX104728 were invited to enroll in BEX104526 for long-term follow-up. Participants were evaluated in Study BEX104728 and Study BEX104526 for up to 15.6 years. ]

Nadir is defined as the lowest laboratory value recorded following the administration of study medication. Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells.

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Ages Eligible for Study:

18 Years and older (Adult, Senior)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria

Subjects had histologically-confirmed NHL.

Subjects with low-, intermediate-, or high-grade histologies, according to the International Working Formulation.

Subjects had relapsed after or had failed to respond to at least 1 prior chemotherapy regimen.

Subjects had evidence that their tumor tissue expressed the CD20 antigen.